I don’t know about the whole country, because there’s a lot of low-density space where it’s hard to justify this level of infrastructure cost.

But the Quebec City-Windsor corridor absolutely needs high-speed rail because it includes roughly half of Canada’s population. It’s even conveniently arranged in a straight line! Driving in this region is hindered by tons of traffic, and flying has huge carbon costs. Rail should be the default way to get around in this region.